(i) Technical Field
The present invention relates to a holographic recording apparatus, a holographic reproducing apparatus, a holographic recording method, and a holographic reproduction method.
(ii) Related Art
A holographic recording and reproducing method is a method for recording or reproducing digital data by means of recording or reproducing, as a hologram, signal light in which binary digital data “0 and 1” are digitally imaged as “bright and dark”, for example. In the case of a Fourier transform hologram, the signal light is subjected to Fourier transform by means of a lens, and a Fourier-transformed image is irradiated on an optical recording medium. Simultaneously, reference light which interferes with the signal light to generate interference fringes is also irradiated on the optical recording medium.
When the signal light and the reference light are spatially overlapped and recorded on a common optical axis, the signal light and the reference light interfere with each other over a wide area in the optical recording medium. In this case, there is a necessity for separating the signal light and the reference light from each other when the hologram is reproduced.